Embolus Removal Device with Blood Flow Restriction and Related Methods

ABSTRACT

The present invention provides devices for removing an embolus or thrombus. The device includes an elongate member configured for insertion into the vasculature, an expandable member that extends from the distal end of the elongate member, and a flow restrictor associated with a proximal portion of the expandable member. The expandable member is configured to transition from a compacted state to an expanded state, in which the expandable portion engages with the embolus. The flow restrictor is configured to restrict blood flow and generate a low pressure zone at a location in the vasculature that is distal to the flow restrictor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Non-provisional Ser.No. 14/082,019, filed Nov. 15, 2013, which claims the benefit of andpriority to U.S. Provisional Ser. No. 61/768,336, filed Feb. 22, 2013,and U.S. Provisional Ser. No. 61/832,786, filed Jun. 8, 2013. Thecontents of the aforementioned applications are incorporated by thisreference as if fully set forth herein in their entirety.

TECHNICAL FIELD

This invention generally relates to devices and methods useful for clotretrieval and removal devices to treat, among other things, ischemicstroke.

BACKGROUND

Currently, the FDA-approved treatment options for an acute ischemicstroke include intravenous (IV) delivery of clot dissolving medicine andmechanical thrombectomy.

For treatment use clot dissolving medicine, the thrombolytic agent(Tissue Plasminogen Activator (t-PA)) is injected into the vasculatureto dissolve blood clots that are blocking blood flow to theneurovasculature. Intravenous t-PA is currently limited in use becauseit must be used within a three hour window from the onset of a strokeand can result in an increased risk of bleeding. This standard of careleaves room for upgrading, lower aisle profiles and is only theappropriate approach to treatment for a limited class of individuals,groups and temporally-limited exigent cases.

The second option includes using mechanical thrombectomy devices. Suchdevices are designed to physically capture an embolus or clot and removeit from the blocked vessel, thereby restoring blood flow. The majoradvantage of the mechanical thrombectomy device is it can expand thetreatment windows from 3 hours to over 10 hours.

Some existing mechanical thrombectomy devices used for increasing bloodflow through an obstructed blood vessel include: 1) a filter trapdesigned and built to collect and remove emboli; 2) a cork-screwedguidewire like device to retrieve embolus; and 3) a stent like deviceconnected to a delivery wire to retrieve embolus. Filter thrombectomydevices suffer from the following disadvantages. The filters tend to becumbersome and difficult to delivery, deploy and a larger profile guidecatheter may be needed to fully remove the embolus. In addition, it isdifficult to coordinate precisely and predictably a desired movement toposition the device properly in the vessel. The device can drift withinthe vessel, twist, or not be adequately conforming to the vessel walland, therefore not effective for removing embolus. Cork-screwedguidewire devices pose a disadvantage because they can only capture andremove emboli that are firm or subject to certain mechanical variablessuch as being held together by itself as one piece. Stent-likemechanical thrombectomy devices are not capable of capturing smallemboli that break off from the large embolus if any, and can lead tocomplications such as blockage of distal smaller vessels, vesseldissection, perforation and hemorrhage arise as a result ofover-manipulation in the vessel.

Disadvantages common to all of the devices described above include, forexample: 1) the device may capture an embolus, but then lose grasp of itand migrate/deposit it incidentally in another area of theneurovasculature, creating the potential for a new stroke in a differentpart of the neurovasculature; 2) the device is not capable to capturethe small embolus break off from the major embolus and prevent it frommigrating to a more distal area of the neurovasculature; 3) the relativelarge device profile prevents it from treating the distal small diametervessels.

Another disadvantage to existing mechanical thrombectomy devices is thatthey are built using two or more distinct pieces that require eitherjoints or bonding between the delivery system and the treatment device.This connection of the pieces generally results in a weakness in thedevice that can result in an unintentional separation of the two pieces,possibly leaving the treatment device in the body during embolusretrieval. Also, the treatment portion of mechanical thrombectomydevices (particularly stent like devices) tend to be cut from tubingthat is larger than the delivery system, thus making the treatmentportion the limiting factor in terms of minimizing the compacted profileof the device, requiring larger access systems and greater deliveryforce to deliver the device.

Other flaws in the current mechanical thrombectomy designs include poorvisibility/radiopacity, lack of variation in the delivery portion toenhance and improve deliverability, and lack of coatings or modifiedsurface textures on the treatment portion to enhance embolus affinity,etc. In conclusion, there is a great need for improved devices, devicesystems, and methods for increasing blood flow through a blood vessel asdescribed herein. None of the existing medical mechanical thrombectomydevices address all necessary needs to date.

SUMMARY OF THE DISCLOSURES

The present invention is directed to a device for removing emboli andother luminal blockages. Devices of the invention include, generally, anexpandable treatment member for removing an embolus and a flowrestrictor associated with a proximal end of the expandable treatmentmember. The expandable treatment member is typically an expandable cageor mesh coupled to an elongate delivery shaft. In use, the expandablemember is position within or distal to an embolus within a blood vesseland then transitioned into an expanded state. Expansion of theexpandable treatment member engages the treatment member with theblockage (e.g., thrombus, embolus, atheroma, fatty deposits, etc.). Inaddition, the expansion of the treatment member causes the proximal flowrestrictor to likewise expand. During treatment, expansion of theproximal flow restrictor advantageously limits or restricts forwardblood flow and creates a low pressure zone within the blood vessel atlocations distal to the flow restrictor. The low pressure zone acts likea vacuum to assist in removal of the embolus from the blood vessel.After expansion, the expandable treatment member and the emboli engagedwith the treatment member are removed from the blood vessel.

According to certain aspects, devices of the invention include anelongate member comprising a distal end, an expandable treatment memberextending from the distal end of the elongate member, and a flowrestrictor associated with a proximal portion of the treatment member.The elongate member is configured to deliver the expandable treatmentmember to a treatment site within a body lumen (e.g., location ofembolus within a blood vessel). The expandable treatment membertransitions from a compacted state to an expanded state. Duringdelivery, the expandable treatment member is preferably in the compactedstate to allow for easy transport of the expandable treatment member tothe location of the embolus. The expandable treatment member may beexpanded within or distal to the embolus to engage the embolus forremoval. The expandable treatment member can also be expanded in alocation in the vessel, so that the embolus is located in a positionbetween the proximal restrictor and the distal end of the expandabletreatment member; in other words, at least portion of the expandabletreatment member is distal to the embolus. The flow restrictor isassociated with a proximal portion of the expandable treatment member,and expands in conjunction with the expansion of the expandabletreatment member. The proximal flow restrictor functions generally asdescribed above.

The components (delivery member 105, expandable member 113, ortransition member 115) of the removal device 111 may be formed fromseparate pieces of material or formed from a single piece of material.In certain embodiments, the elongate delivery member and the expandabletreatment member are constructed from a single/unitary piece ofmaterial, thus eliminating any joints or bonding of the separate memberstogether. This construction improves the strength of the system as awhole and greatly reduces the possibility of the two membersunintentionally detaching from each other during extraction of theembolus. In addition, the elongate delivery member and the treatmentmember, when compacted, may have the similar size profile which reducesthe amount of force required for delivery and provides access intosmaller vessels or other lumens.

In certain embodiments, the expandable treatment member is a frame withplurality of openings. Frame members or struts form the body of theframe and define the plurality of openings. In certain embodiments, theframe members are a plurality of intersecting wires or other threads.The frame members may form a mesh or cage-like structure that defines aplurality of openings. When expanded, the frame receives the embolusthrough the openings and within the frame, thereby engaging the embolusfor removal. In certain embodiments, the expandable treatment membercomprises a plurality of protrusions on the frame. The plurality ofprotrusions further engages the embolus for removal. As an alternativeto or in addition to the plurality of protrusions, the expandabletreatment member may include one or more surface modifications ortreatments. For example, the surface of the expandable treatment membermay be rough to improve clot adhesion.

As discussed, the flow restrictor restricts forward blood flow andgenerates low pressure within a vessel at locations distal to the flowresistor in order to assist in removal of the embolus or other blockage.Preferably, the flow restrictor is designed to transition from acompacted state to an expanded state in response to the expansion of theexpandable treatment member. In certain embodiments, the flow restrictorsurrounds an inner surface or diameter of a proximal portion of theexpandable treatment member. In other embodiments, the flow restrictorsurrounds an outer surface or diameter of a proximal portion of theexpandable treatment member. In further embodiments, the flow restrictorsurrounds both the inner and outer surfaces or diameters of the proximalportion of the expandable treatment member. The flow restrictor maycover a length extending between a proximal end of the expandable memberto about ½ of the length of the expandable member. In other embodiments,the flow restrictor may cover a length extending between a proximal endof the expandable member to about ¼ of the length of the expandablemember. The flow restrictor is typically a film, membrane, or nettedmaterial. In certain embodiments, the flow restrictor is a polymericfilm or membrane. In other embodiments, the flow restrictor is a braidedor woven net formed from a metal, polymer, or combination thereof. Thetype and material of the flow restrictor may be chosen based on thedesired coverage (i.e. amount of flow to be restricted).

A medical mechanical thrombectomy device and methods useful forincreasing blood flow through a blood vessel are described herein. Ingeneral, a device system includes an elongate member (proximal portion)and an expandable member (distal portion) fabricated from a single pieceof super elastic or shape memory biocompatible material (tubing). Theexpandable member is configured to be inserted into a blood vessel anddefines multiple spaces/openings in a wall of the expandable member. Theexpandable member generally has a compacted configuration for deliveryand insertion into the target location of a blood vessel and an expandedconfiguration in which the expandable member to engage/receiveembolus/clots with the multiple space/openings on it. The proximalportion/end of the expandable member has a flow block feature to blockthe blood flow when the device is expanded during the procedure.

The device can be made from either metallic biocompatible material (suchas Nitinol, stainless steel, Co—Cr base alloy, Ta, Ti, etc.) or polymerbased biocompatible material (polymers with shape memory effect, PTFE,HDPE, LDPE, Dacron, Polyester, etc.). For ischemic stroke treatment, theexpandable stent-like member must be flexible enough to negotiate thetorturous vasculature of the brain and without modifying the vesselprofile at the target location. The profile of the expandable stent-likemember must be small enough to reach target treatment site as known toartisans.

The expandable member can be fully or partially coated with chemical(s),drug(s) or other bioagents to prevent clotting and/or for the betteradhesion between the device and embolus. The device surface can betreated to form different surface layer (oxidation layer, Nitro orcarbonized or N—C-combined surface layer, etc.) for better adhesionbetween device and embolus. The device strut surface can bemechanically, chemically, or electrochemically treated to form “rough”surfaces for better adhesion between devices and emboli.

Radiopaque markers (marker coils, marker bands, Radiopaque wire(s),Radiopaque coatings, etc.) are integrated into the treatment device onthe distal portion and proximal portion; or through the entire innerlumen of the treatment portion either partially or entirely to helpvisualize and position the device under standard fluoroscopy equipment.

The transition portion of the device is between the delivery portion andexpandable treatment member. In embodiments that include a deliveryportion and expandable member are formed from a unitary piece ofmaterial, the transition portion is seamless because no joints orbonding are required to connect the delivery portion to the expandabletreatment member. The transition portion may be modified with a numberof variations to vary flexibility by having straight tubing, spiral cutthrough the wall thickness, or spiral cut partially through the wallthickness. When spiral cut, the flexibility can be varied throughvariable pitch sizes across the length. The transition portion can becovered by polymer tubing/layers/covers for the optimization of thedevice deliverability and the surface smoothness.

The inner lumen in the entire device can be used for the local drugdelivery in the vasculature if needed. Following paragraphs describe thedetails of each device component.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, reference is herebymade to the drawings, in which:

FIG. 1 depicts a side profile of the clot removal device, according toembodiments of the present disclosure;

FIG. 2 depicts a side profile of the clot removal device of FIG. 1 fromanother angle.

FIG. 3 depicts the expandable treatment member in the extended position.

FIG. 4A is an example of a transition portion of the device with aspiral cut through the entire wall thickness.

FIG. 4B is an example of a transition portion of the device with aspiral cut partially through the entire wall thickness.

FIG. 5A is an example of a transition portion of the device with aspiral cut configuration showing variable pitch sizes.

FIG. 5B is an example of a transition portion of the device with aspiral cut configuration through the entire wall thickness.

FIG. 6A-6I are illustrate proximal flow restrictors on the proximalportions of the expandable member.

FIG. 7 illustrates a flow restrictor extending across the expandabletreatment member.

FIG. 8 illustrates front and side views of a proximal flow restrictor,according to certain embodiments.

FIG. 9 illustrates a braided proximal flow restrictor surrounding theouter diameter of a proximal portion of the expandable member.

FIG. 10 illustrates a spherical proximal flow restrictor.

FIG. 11A illustrates the expandable treatment member and flow restrictorin the compacted configuration, according to certain embodiments. Theflow restrictor is inside the inner surface/diameter of the expandabletreatment member.

FIG. 11B illustrates the expandable treatment member and flow restrictorin the expanded configuration, according to certain embodiments. Theflow restrictor is inside the inner surface/diameter of the expandabletreatment member.

FIG. 12A illustrates a cross-section of the expandable treatment memberin the compacted configuration, according to certain embodiments.

FIG. 12B illustrates a cross-section of the expandable treatment memberin the extended configuration, according to certain embodiments.

FIGS. 13A-13B illustrate deployment of the expandable treatment memberfrom a delivery sheath.

DETAILED DESCRIPTION

The present invention is directed to a device for removing emboli andother luminal blockages. The device includes an expandable treatmentmember, such as mesh or cage, that is associated with a proximal flowrestrictor. During treatment, the expandable treatment member isposition within or distal to an embolus within a blood vessel and thentransitioned into an expanded state. In certain embodiments, theexpandable treatment member's normal state is the expandedconfiguration, and the expandable treatment member is compacted anddelivered to the treatment site in the compacted configuration through adelivery sheath. The expandable treatment member is deployed from thedelivery sheath, which causes it to return to its normal expandedprofiled by the elastic energy stored in the device. Expansion of theexpandable treatment member engages the expandable treatment member withthe blockage (e.g., thrombus, embolus, atheroma, other fatty deposits,etc.). In addition, the expansion of the expandable treatment membercauses the proximal flow restrictor to likewise expand. Expansion of theproximal flow restrictor advantageously limits or restricts forwardblood flow and creates a low pressure zone within the blood vessel atlocations distal to the flow restrictor. The low pressure zone acts likea vacuum to assist in removal of the embolus from the blood vessel.After expansion, the expandable treatment member and the emboli engagedwith the expandable treatment member are removed from the blood vessel.

In certain embodiments, the expandable treatment member's normal stateis the expanded configuration, and the expandable treatment member iscompacted and delivered to the treatment site in the compactedconfiguration through a delivery sheath. The expandable treatment memberis deployed from the delivery sheath, which causes it to return to itsnormal expanded profiled by the elastic energy stored in the device.

Devices of the invention are suitable for removal of blockages in bodylumens, and are particularly well suited for removal of thrombi, emboli,or atheroma in the vasculature, including those in arteries and veins.It is understood that the dimensions of the device may be modified tosuit a particular application. For example, devices of the inventionused for treatment of deep vein thrombosis may have a largercross-section than devices of the invention used for treatment of brainischemia.

The delivery devices of the invention are described in more detail belowwith reference to the figures.

FIGS. 1 and 2 illustrate various views of the clot removal deviceaccording to certain aspects. FIG. 1 illustrates a front view of theclot removal device, and FIG. 2 illustrates a side view of the clotremoval device of FIG. 1. As indicated in FIGS. 1 and 2, the clotremoval device 111 includes a proximal end 103 and a distal end 101. Theclot removal device 111 includes the following main components: adelivery member 105, a transition member 115, and expandable treatmentmember 113. Note: the components of FIGS. 1 and 2 are not drawn to scalein relationship to each other.

The delivery member 105 is an elongate body or shaft. The deliverymember 105 terminates at the proximal end 103 of the device 111. Thedelivery member 105 is designed to push or drive the expandable memberto a treatment site (e.g. location at or near the embolus). Preferably,the delivery portion is formed from a material of enough rigidity todrive the expandable member through the vasculature. In certainembodiments, the proximal end of the delivery member 105 includes ahandle for easy maneuvering of the device 111 within the vasculature.The delivery member 105 may about 40 cm or longer. In some embodiments,the delivery member 105 is about 100 cm or longer. In some embodiments,the delivery member 105 is about 190 cm or longer. A distal end of thedelivery member 105 is associated with the proximal end of thetransition member 115. In some embodiments, the delivery member 105 iscoupled to the transition member 115, e.g. via a joint. In otherembodiments, the delivery member 105 is formed from the same unitarypiece of material as the transition member 115 such that the deliverymember 105 seamlessly changes into the transition member 115.

The transition member 115 is typically more flexible than the deliverymember 105. The flexibility of the transition portion 115 allows thedelivery of the expandable member 113 through the tortuous vasculature.The transition member 115 may be of the same flexibility or rigidityacross its length or the transition member 115 may have variableflexibility or rigidity across its length. For example, a proximal endof the transition member 115 may be more rigid than the distal end ofthe transition member 115. The length of the transition member 115 maydepend on the treatment application of the device 111. For example, thetransition member 115 may be smaller in devices used to remove cerebralemboli and may be larger in devices used to remove emboli near the heartor deep vein. Suitable lengths for the transition member 115 range, forexample, from about 5 cm to about 50 cm. A distal end of the transitionmember 115 is associated with a proximal end of the expandable treatmentmember 113. In some embodiments, the transition member 115 is coupled tothe expandable treatment member 113, e.g. via a joint. In otherembodiments, the transition member 115 is formed from the same unitarypiece of material as the expandable treatment member 113 such that thetransition member 115 seamlessly changes into the expandable treatmentmember 113.

The expandable treatment member 113 is used to remove the embolus orother blockage within a vessel. The expandable treatment member 113transitions from a compacted configuration to an expanded configuration.When in the compacted configuration, the expandable treatment member 113has a smaller cross-section than when the expandable treatment member113 is in the expanded configuration. In certain embodiments, the bodyor frame of the expandable treatment member 113, when in the compactedconfiguration, is elongated. FIG. 11A illustrates the expandabletreatment member 113 in the elongated, compacted configuration, and FIG.11B illustrates the expandable treatment member 113 in a shorter,expanded configuration. In other embodiments, the body or frame of theexpandable treatment member 113, when in the compacted configuration, iscondensed, folded, or wrapped around itself. FIG. 12A illustrates anexemplary cross-section of the expandable treatment member 113 wrappedand folded around itself, while in the compacted configuration. FIG. 12Billustrates the same cross-section of the expandable treatment member113 when in the unwrapped, expanded configuration.

Typically, the expandable treatment member 113 transitions from thecompacted configuration to the expanded configuration when theexpandable treatment 113 is deployed/released from an outer deliverysheath, like microcatheter, used in conjunction with and surrounding theremoval device 111. In use, the expandable member 113 is eitherpositioned within the embolus or distal to the embolus and thendeployed. The expandable treatment member 113 can also have a lengthlonger than that of the embolus, in use, the expandable treatment member113 can go beyond both ends of the embolus (for example, embolus locatein the middle portion of the expandable treatment portion), and toengage embolus to remove it from the vessel. Upon deployment, theexpandable treatment member 113 expands to engage with the embolus forremoval. In dealing with long emboli, the device can also be used toremove the embolus from the proximal portion to distal with multiplepasses, until entire embolus is removed.

According to certain embodiments, the body or frame of the expandabletreatment member 113 includes frame members 104 (or struts) that definea plurality of openings 102. The frame members 104 also define an innerlumen 108. In certain embodiments, the frame members 104 are a pluralityof intersecting wires or threads. The configuration of the frame members104 may form a mesh or cage-like support structure. The frame members104 of the expandable member 113 may forms angles with the longitudinalaxis of the device in the range from at least about 5 to approximately175 degrees. The frame members 104 can have twists along theirlongitudinal axes. When expanded, the expandable treatment member 113receives the embolus within the frame, thereby engaging the embolus forremoval. That is, a portion of the embolus may enter the inner lumen 108of the expandable member 113, and thus integrating the embolus with theexpandable member 113 for removal. The length of the expandable member113 may depend on the treatment application of the device 111.Preferably, expandable member may range from about 0.5 cm to about 15 cmin length (while smaller and longer lengths are also contemplated). Theexpandable treatment member 113 can include a tapered distal section.The tapered distal section assists in collecting small embolus breakoffs from major clot(s) and preventing them from migrating to a moredistal area of the vasculature.

The device 111 may also include markers 116, 118 at or near the proximaland/or distal ends of the expandable member 113. The markers 116, 118are preferably formed from a material that is visible to an imagingmodality (such as x-ray, angiogram, or other external imaging modality).In certain instances, the material is radiopaque. The markers 116, 118may be rings, bands, wires, or coils or other elements surrounding thejunctions at the proximal and distal ends of the expandable member 113.In certain embodiments, the marker 116 forms the joint between thetransition member 115 and expandable member 113.

In certain embodiments, the expandable treatment member 113 includes aninner radiopaque shaft 116. The shaft 116, like markers 116, 118,increases the visibility of the expandable member 113 by externalimaging modalities during the procedure. The shaft 116 may be formed asa unit with the markers 116, 118 (e.g., forming a dumbbell likestructure).

In preferred embodiments, the delivery member 105, transition member115, and expandable member 113 are all formed from a unitary piece ofmaterial. By using a unitary material to form those components, thedevice 111 does not include joints connecting the components. Theunitary piece of material is typically tubing that is cut to form thedistinct components. The device 111 is made by laser cutting, mechanicalmachining, chemical machining, electrochemical machining, EDM, andrelated techniques known to artisans. Preferably, the material isbiocompatible, super elastic, and/or exhibits shape memory properties.Suitable materials include Nitinol and alloys thereof. The constructionof the device 111 from a unitary piece of material dramatically reducesthe possibility of an unintentional separation of the expandable member113 from the delivery member 105 or the transition member 115.

The following describes the various components of the removal device 111and additional features of the removal device 111.

FIGS. 4A-4B show examples of the transition member 115 of the design.The transition member, as shown in FIGS. 4A-4B, is a tube with a spiralcut extending partially through the thickness h of the tube. By onlypartially cutting into the thickness h of the tube, a plurality ofgrooves 216 is formed on the surface of the tube (as best shown in FIG.4B). The width or pitch w (see FIG. 4B) of the spiral cut may be thesame or vary across the length of the transition member 115. As shown inFIG. 4A, the spiral cut transitions from a first width w1 to a secondwidth w2. Particularly, the width decreases from w1 to w2 across thelength of the transition member 115.

FIGS. 5A-5B show examples of the transition member 115 of the removaldevice 111, according to another embodiment. The transition member, asshown in FIGS. 5A-5B, is a tube with a spiral cut extending completelythrough the thickness h of the tube. By cutting into the entirethickness h of the tube (best shown in FIG. 5B), the tube has aspring-like profile. The width or pitch w (see FIG. 5B) of the spiralcut may be the same or vary across the length of the transition member115. As shown in FIG. 5A, the spiral cut transitions from a first widthw1 to a second width w2. Particularly, the width decreases from w1 to w2across the length of the transition member 115.

Preferably, the device 111 of the invention includes a proximal flowrestrictor. The proximal flow restrictor is associated with the proximalportion or end of the expandable treatment member 113. The proximal flowrestrictor may be positioned proximal to the proximal end of theexpandable member, on, within or surrounding the proximal portion of theexpandable member, or both. Ideally, the proximal flow restrictorextends any length between the proximal end and the middle of thetreatment member 113. The proximal flow restrictor is typically amaterial that at least partially surrounds the inner or outer surfacesor diameters of the proximal end of the expandable treatment member 113.The proximal flow restrictor may also be one or more layers of thematerial. In some embodiments, the proximal flow restrictor surroundsboth the inner and outer surfaces of the treatment member 113. Theproximal flow restrictor may be a mesh, membrane, or deposited coating.In addition, the flow restrictor is formed from a braided material. Themesh or membrane may have varying porosity, depending on the preferredamount of flow blockage desired. The proximal flow restrictor may beformed from a polymer, a metal, a plastic, a fabric formed fromsynthetic or natural fibers, etc. Specific examples of materials for theflow restrictor include Nitinol, Pt, Ta, Co—Cr, stainless steel,polyether ether ketone, polytetrafluoroethylene, polyether block amides,polyethylene, and combinations thereof. Preferably, the flow restrictoris biocompatible.

The proximal flow restrictor may be formed as part of the expandablemember 113 or coupled to the expandable member 113. One end (eitherproximal or distal end) of the flow restrictor can be loose or free tomove, to accommodate the length change or variation during the deliveryand expansion processes. The proximal flow restrictor may be coupled tothe expandable member mechanically, thermally (laser or soldering),chemically, adhesively, or using heat shrink technology.

Like the expandable member 113, the proximal flow restrictor can have afirst smaller compacted profile to make the delivery through a deliverysheath or microcatheter possible. The flow restrictor can have a secondlarger expanded diameter/profile when the device is deployed from thedelivery sheath to block, limit, or restrict the blood flow. Typically,the flow restrictor expands in unison or in response to the expansion ofthe expandable treatment member 113, as described hereinafter. During athrombectomy procedure using the present device 111, the proximal flowrestrictor expands in response to expansion of the expandable treatmentmember 113. The expansion of the proximal flow restrictor advantageouslylimits or restricts forward blood flow and creates a low pressure zonewithin the blood vessel at locations distal to the flow restrictor. Thelow pressure zone acts like a vacuum to assist in removal of the embolusfrom the blood vessel.

FIGS. 6A-6I illustrate various embodiments of the proximal flowrestrictor 600 on the expandable treatment member 113. FIGS. 6A and 6Billustrate the proximal flow restrictor 600 of varying porosity. Thegreater the porosity the lesser the vacuum created in the vessel due tothe presence of the flow restrictor 600. As shown in both FIGS. 6A and6B, the flow restrictor 600 is uniformly covering the proximal portionof the expandable member 13. FIG. 6C illustrates a flow restrictor thatonly covers the proximal openings 102 formed by the frame members 104 ofthe proximal portion of the expandable member 113. The proximal flowrestrictor 600 may have various patterns or textures for restrictingblood flow. FIG. 6D illustrates a flow restrictor 600 with horizontaltexture, and FIG. 6E illustrates a flow restrictor 600 with verticaltexture. FIG. 6F illustrates a flow restrictor 600 formed from a braidedor netted material. FIGS. 6G-61 illustrates flow restrictors 600 formedfrom deposition processes with different coverage patterns. Thedeposition processes may include, for example, physical vapordeposition, chemical vapor deposition, etc. FIG. 6G illustrates adeposited flow restrictor 600 surrounding the outer surface of theexpandable treatment member 113. FIG. 6H illustrates a deposited flowrestrictor 600 disposed within the proximal openings 102 of theexpandable treatment member 113. FIG. 6I illustrates a deposited flowrestrictor 600 covering a proximal portion of the expandable treatmentmember 113.

In addition, FIG. 8 illustrates front, back, and side views of aproximal flow protector 600, according to certain embodiments.

The flow restrictor 600 may expand across a length of the expandabletreatment member 113 from the proximal end toward the distal end. Thelength may be, for example, ¼, ⅓, ½, ⅔, ¾ of the body or the entirelength of the body. In certain embodiments, the flow restrictor 600 mayextend (partially or entirely) from the proximal end to the distal endof the expandable member 113 with varying degrees of coverage. Forvarying coverage, the flow restrictor may be present on the expandablemember 113 in varying patterns. FIG. 7 illustrates a front view and aside view of an expandable member 113 with a proximal flow restrictor600 having a spiral pattern across its entire length.

The flow restrictor 600 may also have different profiles. Typically, theflow restrictor 600 substantially conforms to an inner or outer surfaceof the expandable member 113. FIG. 9 illustrates proximal flowrestrictor 600 that is a braided net conforming to the proximal end ofexpandable member 113. Alternatively, the flow restrictor 600 may have adifferent shape than the proximal portion of the expandable member 113.For example, the flow restrictor may have a spherical (FIG. 10),cylindrical or rectangular shape, which can be within a proximal portionof the expandable treatment member 113, proximal to the expandabletreatment member (FIG. 10), or surrounding a proximal portion of theexpandable treatment member.

FIG. 10 shows an exemplary configuration of the flow restrictor 600 witha spherical or substantially spherical structure. As shown, thespherical structure is braided, but it may also be made by otherprocesses (e.g. by laser cutting). The spherical structure can also befabricated from the same piece of tubing (e.g, Nitinol tubing) with thatof the device by laser cutting or chemical processes and then shape setto a larger diameter than the raw Nitinol tubing. The sphericalstructure can also be fabricated from the same piece of Nitinol tubingwith that of the device by laser cutting or chemical processes and thenshape set to a larger diameter than the raw Nitinol tubing.

In addition to removal device 111 of the invention, the proximal flowrestrictor 600 can be combined and used with any existing clot retrieverdevices to restrict forward blood flow and help remove the clot fromvasculature. For example, a proximal flow restrictor 600 of theinvention may be used in combination with a morcellating device forremoving emboli. In such instance, the proximal flow restrictor 600 isplaced proximal to a blade used to morcellate the emboli.

As discussed above, radiopaque markers can be attached on any portion ofthe device for positioning (such as markers 116 and 118). Another way togain visibility during use of the clot removal device 111 is to run aradiopaque material through the entire or partial lumen of the clotremoval device 111.

The device 111 can have surface treatment on one or more of its variouscomponents (e.g. delivery member, transition member, expandable member,flow restrictor) to improve performance for those components of thedevice. For example, one or more components can either be coated orcovered by typical biocompatible materials for lubricity entirely orpartially. In addition, one or more components can have a positive or anegative charge for improved clot adhesion. Particularly, a surface ofthe expandable member 113 can have either a positive or negative chargefor improved clot adhesion. In another example, the surface of one ormore of the components can also be either mechanically or chemicallytreated to have a rough surface for improved clot adhesion. The roughsurface can be achieved by, for example, 1) porous surface coating orlayer; 2) micro-blasted surface or micro-pinning; 3) irregular strutgeometry or arrangement.

FIGS. 11A and 11B illustrate a preferred embodiment of the expandablemember 113 and flow restrictor 600. FIG. 11A illustrates the expandablemember 113 in the compacted configuration. FIG. 11B illustrates theexpandable member 113 in the expanded configuration. As shown in FIGS.11A and 11B, the flow restrictor 600 is coupled to the proximal innersurface of the frame members 102 of the expandable member 113 such thatthe flow restrictor 600 expands along with expansion of the expandablemember 113. The flow restrictor 600 is braided and forms a pouch-like inthe inner lumen of the expandable member 113 to stop forward blood flowand create a vacuum to assist in clot removal. The frame members 104 ofthe expandable member 104 may include protrusions 340, valleys 330, orboth to assist in clot removal. The protrusions 340 may be located atthe intersection of two or more frame members 104 or along the length ofa frame member 104. Generally, the protrusions are located on theperipheral of the frame. Likewise, the valleys 330 may be located at theintersection of the two or more frame members 104 or along the length ofa frame member 104. In addition, the frame members 104 are intersectingto form openings 102 between the frame members 104. During use, the clotmay enter the expandable member 113 through the openings 102, therebyintegrating/engaging the clot with the expandable member 113 andreducing risk of clots breaking away or getting loose from theexpandable member 113 during removal.

FIGS. 13A and 13B illustrate the expandable member 113 transitioningfrom the compacted configuration (FIG. 13A) to the expandedconfiguration (FIG. 13B), according to certain embodiments. Theexpandable member 113 may transition from the compacted configuration tothe expanded configuration when the expandable member 113 is deployedfrom a delivery sheath 400. For example, a delivery sheath 400 may bepositioned within a blood vessel, and a distal opening 402 of thedelivery sheath may be positioned at or near, or distal to the blockage.The expandable member 113 is in the compacted configuration whendisposed within a lumen of the delivery sheath 400. Once the deliverysheath 400 is placed as desired, the delivery member 105 can be used topush or deploy the expandable member 113 out of the opening 402 of thedelivery sheath 400 and into the treatment area (e.g. into the blockageor distal to the blockage). In some embodiments, the expandabletreatment member 113 is deployed by pushing the expandable treatmentmember 113 in the distal direction via the deliver member 105. In otherembodiments, the expandable treatment member can be released/deployedfrom the delivery sheath 400, by withdrawing the sheath 400 proximatelyto expose the expandable treatment member 113. As the expandable member113 is deployed, the expandable member 113 transitions from thecompacted configuration to the expanded configuration, as shown in FIG.13B.

In summary, the removal devices of the invention have several benefitsover the prior art. The construction of the device from a single pieceallows for a seamless transition from the delivery portion to thetreatment portion, thus removing any joints or bonding of the twoportions together as separate pieces. This improves the strength of thesystem as a whole and greatly reduces the possibility of the two partsunintentionally detaching from each other. Also, because the distaltreatment portion is cut from a piece of material the same size as theproximal delivery portion, it allows the device to be compacted to asimilar size profile giving it delivery advantages including a lowerdelivery force required and requiring small access systems. Additionaldelivery advantages from this design include the ability to manipulatethe flexibility of the delivery system by varying the pitch size. Inaddition, a radiopaque marker can be attached within the lumen of thedevice to improve visualization. Lastly, the treatment portion's surfacecan be altered to enhance embolus affinity by either coating with asubstance or changing the texture by mechanical or chemical means.

Compared with existing mechanical thrombectomy devices, the uniquedevice design included in this invention has the advantage of 1) havingproximal flow block/restriction feature to block the blood distal flowwhen the device is deployed during use; this feature can help toeliminate or reduce the risk of flush or break the clots during theprocedure; 2) being made from a single piece of Nitinol super elasticmaterial (such as tubing, etc.), Nitinol shape memory alloy material, orother biocompatible materials which exhibit super elastic or shapememory properties, thus giving the device a seamless transition fromproximal delivery portion to distal therapeutic portion. Thiseffectively removes any joints or bonding of a delivery wire with thetreatment device, eliminating this physical weakness in the device andgreatly reducing unintentional breakages during devicedelivery/retrieval. Another important advantage of the design disclosedin present invention is varies features (such as spiral cut, helix/coilconfiguration, etc.) can be implemented into device proximal deliveryportion to achieve variable flexibility for easy delivery andnavigation. The flexibility of the proximal delivery portion can varyfrom proximal to distal. For example, the distal portion can be moreflexible than proximal portion. Furthermore, the device can achieve asmaller compacted profile, which reduces delivery and retrieval forceand allows the physician to use smaller microcatheters for delivery tosmaller vessels or the more distal vasculature. During the procedure,the flow restrictor can block the blood flow through the lumen of thedevice and the lumen of the treatment vessel segment, to help engage theclot and eliminate or reduce the risk to break the clot or flush theclots distal to the more distal vasculature.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patentapplications, patent publications, journals, books, papers, and webcontents, have been made throughout this disclosure. All such documentsare hereby incorporated herein by reference in their entirety for allpurposes.

EQUIVALENTS

Various modifications of the invention and many further embodimentsthereof, in addition to those shown and described herein, will becomeapparent to those skilled in the art from the full contents of thisdocument, including references to the scientific and patent literaturecited herein. The subject matter herein contains important information,exemplification and guidance that can be adapted to the practice of thisinvention in its various embodiments and equivalents thereof.

1-21. (canceled)
 22. A device for removing a blood clot in a vessel, the device comprising: an elongate member configured for insertion into the vasculature, the elongate member comprising a distal end; an expandable member comprising a proximal portion that extends from the distal end of the elongate member, the expandable member configured to transition from a compacted state to an expanded state, in which the expandable member engages with the blood clot: and a flow restrictor associated with the proximal portion of the expandable member with the expandable member circumferentially surrounding the flow restrictor, the flow restrictor configured to restrict blood flow and generate a low pressure zone at a location in the vasculature that is distal to the flow restrictor.
 23. The device of claim 22, wherein the expandable member comprises a frame defining a plurality of openings
 24. The device of claim 22, wherein the flow restrictor comprises a metal, a polymer, or a combination thereof.
 25. The device of claim 22, wherein the flow restrictor comprises a material selected from group consisting of a netted material, a braided material, or a thin membrane.
 26. The device of claim 22, wherein the flow restrictor covers a length extending between a proximal end of the expandable member to about ½ of the length of the expandable member.
 27. The device of claim 22, wherein the flow restrictor covers a length extending between a proximal end of the expandable member to about ¼ of the length of the expandable member. 